1. Field of the Invention:
This invention relates to a visual field searching device which is arranged to recognize object positions within a visual field to be searched and is adapted for application to the automatic focusing device of a photographic apparatus and the visual systems of robots or other automatic inspection apparatuses; and more particularly to a device which is capable of recognizing a wide visual field, by consolidating information for each of divided sections of the visual field to permit reduction in size of a storage device and shortening the length of time required in carrying out the ensuing computing operation.
2. Description of the Prior Art:
In the field of photographic cameras or the like, there have been proposed devices arranged to automatically measure a distance to an object for the purpose of enabling a photo-taking lens to be shifted to an in-focus position. However, since these devices are adapted for measuring a distance to an object located in a specific part within a visual field, they are not readily applicable to an apparatus such as a robot of the kind that must operate with incessant cognizance of a whole visual field.
Meanwhile, varied kinds of devices adapted for bringing a robot or the like into cognizance of objects have been known. For example, Japanese Laid-Open Patent Application No. SHO 58-129304 has disclosed a device for measuring a distance and an angle between two points existing in a three dimensional space. Further, Japanese Laid-Open Patent Application No. SHO 58-70108 has disclosed another device. In the latter device, a spot light is projected into a visual field; changes in the luminance of a point on which the spot light is projected are detected by a two dimensional sensor consisting of two TV cameras or the like; and a data for each point within the whole visual field is measured by detecting the position of the projected spot light in a three dimensional coordiate system. However, this device necessitates transformation of the data of the three dimensional coordinate into a data of polar coordinate for controlling the actions of a robot or the like. Besides, in enlarging a visual field, the optical distortion of an image which takes place according as the visual field is enlarged must be corrected. This results either in a prolonged data processing operation or a complex structural arrangement of the data processing device.
A further disadvantage of the prior art devices of the above-stated kind is as follows: For example, the device disclosed in Japanese Laid-Open Patent Application No. SHO 58-70108 is arranged to store the data obtained for every point within a visual field and to perform the ensuing process on the basis of all the data thus stored. Therefore, in case where the whole of a relatively wide visual field is to be subjected to distance measurement, the device necessitates use of storage means of a large capacity and a complex computing operation before recognizing an object by processing all the data.